The traditional archery bow is comprised of a riser having a hand grip and an arrow rest and a pair of resilient limbs attached to each end of the riser. The resilient limbs of the bow flex to produce a stored energy needed to propel an archery arrow. The bow string is attached to the free end of each resilient limb so that when the bow string is drawn back from its initial position by an archer to shoot an arrow, the resilient limbs flex to place the bow string under tension. The further the archer draws the bow string back, the more the resilient limbs of the bow are flexed which imparts a greater amount of stored energy in the bow. When the bow string is released to shoot the arrow, the resilient limbs of the bow snap back to their original position to force the bow string back to its initial position to propel the arrow towards a target. These traditional bows are frequently made of strong composite materials but they do have drawbacks. For instance, once an archer selects a particular archery bow, he is restricted with that bow to a maximum drawing force so that the archer is unable to vary the poundage range for a particular bow. Yet other drawbacks include the holding forces relating to these types of bows; especially when in the full drawn position. In this respect, the stored energy of a traditional bow increases as the bow string is drawn back. Similarly, the holding forces increase as the bow string is drawn back such that the maximum stored energy is generally coupled with the maximum hold force when the bow is in the full drawn position. In that this is the firing position for the bow, the shooter exerts considerable energy in holding the bow in the full drawn position to take aim at the desired target. When using a bow for hunting, this can be very difficult and can cause shots to be rushed and/or off target. Further, this condition limits the amount of stored energy that can be utilized in a traditional bow in that high levels of stored energy produce high holding forces that cannot be overcome by the shooter. Therefore, the traditional bow has limits to its ability to utilize and manage high levels of stored energy. Yet even further, not only is it difficult or impossible to modify the traditional long bow, special equipment is needed to remove the bow string from the bow limbs in that they must be pre-stressed in order to produce the necessary stored energy. While, in some cases, the bow string could be removable, it is difficult and requires a lot of strength.
While traditional bows utilize the limbs to produce stored energy, some prior art bows have attempted to use springs for loading the bow that have not had any real success. An earlier spring loaded archery bow can be seen in the D. M. Holmes U.S. Pat. No. 428,912 which includes a tension spring extending through the riser of the bow. As can be seen, this drastically limits the configuration of the riser which has been found to be an integral part of a bow design. As with many hand operated tools, ergonomics are very important and this spring design adversely affects the riser's ergonomics significantly. Yet even further, the use of a tension spring also greatly increases the objectionable sound that is produced by the system. As can be appreciated, when this spring snaps back to its at rest position, it will wobble and produce noise that is not acceptable when hunting. Yet even further, this spring wobble could likely be felt in riser by the archer which is also not acceptable and which could affect accuracy. Further, the Holmes bow cannot be modified and the stored energy and hold force will be at its highest level at the full draw point just like a traditional bow. Thus, while this bow may be capable of producing higher amounts of stored energy, it is very similar to a traditional bow and does not allow for the management of those higher energy levels. This design is also not adjustable and requires a custom spring that has opposing extensions for connecting the spring to the limbs.
Similarly, U.S. Pat. No. 4,458,657 to Stockmar discloses an archery bow that does not utilized flexible limbs, Stockmar discloses a complicated bow structure with both a main frame and a separate handle grip space forwardly of the frame wherein the bow string tensioning assembly is located forward of the main frame. The bow string tensioning assembly is formed by exposed resilient tubes for tensioning the bow string which are stretched and placed in tension when the bow string of the bow is drawn. By including both a riser and a solid frame, this design drastically increases the weight of the bow. As can be seen, Stockmar recognized this problem by include weight reducing holes in his frame design. Yet further, this design has exposed workings that could be dangerous and which would be drastically impacted by weather changes. As is now, resilient materials, such as those disclosed, will produce greatly different amounts of stored energy in cold weather than in warm weather. Further, by including significant frame and riser designs, this system will create significant blind spots which is especially problematic when quick target acquisition is needed; such as when the bow is used for hunting. The frame design behind the handle grip or riser also creates a design flaw wherein the archer's arm would likely engage this frame structure when firing the bow.
A compound archery bow uses mechanical advantage to overcome many of the shortcomings of the traditional bow and the spring loaded bows that simulate traditional bows to allow for increases in stored energy while managing the holding forces when in the full drawn position. This is typically accomplished by utilizing cams and/or pulleys attached to the limbs of the bow. Again, the limbs act to store energy and can be designed to store greater amounts of energy wherein the limbs of a compound bow are usually much different than those of a traditional archery bow. Further, the cams of a compound bow can be utilized to both increase the stored energy and reduce the hold force when the bow is in the full drawn position which allows the compound bow to direct much greater amounts of energy into the arrow. In that the compound bow attaches the bow string to cams or pulleys to give a mechanical advantage to the bow string, when the bow string is pulled, it causes the cams to rotate and the limbs to bend. Again, the limbs provide the stored energy, but the cams provide mechanical advantage to increase the stored energy and to decrease the hold force in the full drawn position. However, while the hold force may be lower for the full drawn position, it is typically higher before the full drawn position is reached. A compound bow has a rigid handgrip or riser having limbs attached to each end and having the sights and the like attached thereto.
Even though compound bows have overcome many shortcomings in the traditional bow, it also has many limitations; one such limitation is that it is not easily adjustable. As with the traditional bow, the compound bow relies on the stored energy of the flexible limbs which cannot be changed. These flexible limbs are built into the compound bow and cannot be adjusted or modified once the bow is manufactured. However, it has been found that the cams can be utilized to change the dynamics of the compound bow wherein the overall stored energy of the system can be modified by changing the cam configuration. Further, other dynamics can be modified by changing the cams of the bow. However, while the use of rotating cams allows for modifications, these cannot be done easily and typically require expensive equipment that must be used to overcome the high levels of stored energy in the flexible limbs. In this respect, an archer who wants to modify their bow must take their bow to an archery dealer who has the equipment to compress the limbs of the bow sufficiently to loosen the bow string and remove the cam or cams without damaging the flexible limbs that can be very fragile. The same is true for repairs to damaged bows. These cannot be done without specialized equipment. Thus, if a bow is damaged in the field (such as while on a hunting trip), the hunter cannot fix his damaged bow and typically caries a spare bow just for this situation. Even if the hunter did own the necessary equipment, it is not practical to take the needed equipment into the field. Thus, while the compound bows allow for the use and management of higher levels of stored energy, that is essentially the extent of the benefit of these bows. In addition, it has been found that the flexible limbs used in compound bows can fail over time and this is being made worse by the ever increasing amounts of pre-load tension that is being put into these flexible limbs when the bows are strung. This is especially true with crossbows wherein crossbow limbs are being preloaded with such high tension for arrow speed that the limbs often break.
In the York U.S. Pat. No. 7,201,161, disclosed is another spring loaded archery bow that also incorporates a spring in the riser portion of the bow. York discloses a riser that has separate upper and lower spring tensioning assemblies and these assemblies both include a central tension cable that extends within a coil spring to join opposing swoosh shaped cam members. As with the spring mechanism discussed above, this central cable structure is positioned closely to the coil spring and would likely be noisy in operation. Further, separate upper and lower spring tensioning assemblies are contained within the upper and lower rigid limbs of the bow so that the bow retains the appearance of a traditional archery bow. In the Dieziger U.S. Pat. No. 6,055,974 a compound bow has a facilitated draw for allowing a bow string to be more easily drawn and uses a pair of complicated and fragile coil springs string structures that are fully exposed. Further, as with other spring bow systems, while springs are disclosed, these systems do not include structure that van be easily modified for the many archers that may use a single bow. In the L. J. Mulkey U.S. Pat. No. 2,714,377, discloses a complicated spring structure system that surrounds the riser of the bow and which is fully exposed even though it is in close proximity to the archers hands and arms. Similarly, the Guzzetta U.S. Pat. No. 4,756,295 discloses a complicated bow structure that includes linkages extending about the riser of the bow and which are again fully exposed. While the toggle-like assembly may be configured to improve the accuracy and acceleration of the bow, it utilizes a single coil spring and requires many components that would add weight and complexity to the system.
Eklund U.S. Pat. No. 6,698,413 discloses an archery bow includes a solid and rigid frame having no flexing or pivoting components. Conversely, Eklund discloses a bow that uses a rotating wheel to create the necessary stored energy to shoot an arrow. This system includes a lower wheel rotatably mounted to the lower limb that rotatably attached to a self-contained tensioning unit having a variably compressible power coil spring therein. A cam is rotatably mounted to the lower limb between the lower wheel and the tensioning unit and is engaged by a cable which connects the spring with the lower wheel so as to provide a resilient pull to establish a draw weight required to move the bowstring from an at-rest position to a drawn position. While Eklund disclose adjustment to the pull length, this bow system is also not easily modifiable and is significantly out of balance. As can be seen, the vast majority of the bow weight is located on one side of his bow which greatly reduces the ability to aim this bow.
Again, while there are many bow designs, there remains a need for an effective archery bow that is lightweight, reliable, and fully adjustable without needing to take the bow to an archery shop. Further, this bow needs to be capable of producing high shooting speeds, but with low holding forces at full draw. While many of the bows discussed above have some of these features, none have all and many are deficient in many ways. Thus, many of these designs have never been produced.
All of the above-mentioned patents are incorporated by reference herein as background material. Also incorporated by reference is the printout from Hunter's Friend which is printed from huntersfriend.com.